Solar PV in a power-cut

[Ferdinand]

Does one of our experts know whether Solar PV panels generate electricity for the house during a power cut?

 

AFAICS there are a few relevant issues:

 

1 - Grid connected panels are presumably auto-disconnected to avoid feeding power to the staff doing repairs.

2 - Is this different depending on whether it is a grid-connected setup or a self-done standalone?

 

I expect it depends on what is disconnected and how.

 

Any comments are most welcome.

 

Ferdinand

 

[tonyshouse]

Disconnects the instant the grid goes down 

[joth]

Basically, no, solar PV never will. The second-by-second variation in sun hitting the panels would make it very unstable source, and unable to respond to a sudden increase in demand like the kettle being put on would cause a house brown out. So all PV inverters include automatic cutout function to avoid "islanding" in the case of grid outage.

Many (most?) domestic batteries do support off-grid mode though, and these will often generate the appropriate waveform to "trick" the PV to think it's still connected to the grid and keep working. So second by second variations are buffered over by the battery, either consuming excess generation (charging the battery) or backfilling the gaps in generation by discharging the battery. It's possible the battery will even speed up or slow down the frequency it generates as the battery fills up, to signal to the PV to back off generation (analogous to how the grid frequency changes at times of over or under supply, and PV inverters are required to respond to as part of G98 regulations)

 

There's also DC coupled batteries that solve all of this within the PV inverter.

 

More specific answers would depend on exact make/model combos chosen.

 

[SteamyTea]

31 minutes ago, joth said:

Many (most?) domestic batteries do support off-grid mode though, and these will often generate the appropriate waveform to "trick" the PV to think it's still connected to the grid and keep working

Dont most grid tied inverters also sense the grid impedance? Which can be tricked as well.